For hundreds of years, the standard soil-tilling device has been the mold-board plow. The traditional shape for the mold-board plow includes a curved blade converging to a point in the forward direction, the curvature acting to lift a slice of earth and turn it over. Typically, several such mold plow blades are mounted on a single frame in a diagonal pattern.
More recently, a differently shaped plow has been introduced, called the bentleg plow. Such a plow is described by Williams, M., in an article entitled "Enter--A New Kind of Plow", appearing in the October, 1981 edition of Power Farming. The known shape of a bentleg plow includes an upper leg in the form of a flat plate with its leading edge rotated ahead by about 25 degrees, and a lower leg which is bent at about 45 degrees to the side. The lower leg also has a forward rotation of its leading edge. When the bentleg plow is drawn through soil, the lower leg tends to loosen the soil above it.
The known bentleg plow is typically made from an appropriately shaped piece of steel plate, with the lower leg portion bent with respect to the upper part about a line which is parallel with the direction in which the bentleg plow is drawn through the soil. This means that the lower leg lies in an oblique plane which is parallel with the direction of movement.